Embodiments of the present invention relate to components for substrate processing chambers.
A substrate processing chamber is used to process a substrate such as for example, a semiconductor wafer or display, in an energized process gas. The processing chamber typically comprises an enclosure wall that encloses a process zone into which a gas is introduced and energized. The chamber may be used to deposit material on the substrate by chemical or physical vapor deposition, etch material from a substrate, implant material on a substrate, or convert substrate layers such as by oxidizing layers or forming nitrides. The chamber typically includes a number of internal chamber components such as for example, a substrate support, gas distributor, gas energizer, and different types of liners and shields. For example, the liners and shields can be cylindrical members surrounding the substrate to serve as focus rings to direct and contain plasma about the substrate, deposition rings that prevent deposition on underlying components or portions of the substrate, substrate shields, and chamber wall liners.
Ceramic materials are often used to form the internal chamber components, especially those components that are exposed to the energized gas or plasma, and consequently, are subject to high temperatures and erosion. Ceramic materials such as alumina and silica are crystalline whereas silica glasses have no long range order. Ceramics typically exhibit good resistance to erosion by the energized gases, and consequently, do not have to be replaced as often as metal alloys. Ceramic components also reduce the generation of particles in the chamber that result from the erosion of components. Ceramic components can also withstand high temperatures without thermal degradation. Quartz components are particularly useful for plasmas that would corrode other materials, such as plasmas containing fluorine species.
However, ceramic materials are subject to brittle failure modes and often crack or chip in use in the chamber or during handling in the replacement or cleaning of the component. Amorphous and microcrystalline materials are particularly susceptible to brittle failure through crack propagation. In amorphous materials, such as glass, surface microcracks propagate on an atomic level because glass has short-range order without any long-range order. Microcrystalline materials, such as quartz, have grains with a surface that can have intragranular microcracks that are through single grains, intergranular microcracks that extend around grains and along grain boundaries, as well as transgranular microcracks that cut across adjacent grains. Of these, the intergranular microcracks that extend around the microcrystalline grains of the quartz are generally the most culpable for crack propagation and often lead to chipping and cracking of the component.
Thus, it is desirable to have a ceramic component made from microcrystalline or amorphous ceramics that exhibits reduced chipping and cracking. It is further desirable to fabricate such ceramic components with lower failure rates during use. It is also desirable for the ceramic components to be able to withstand the energized gas environment in the chamber without excessive erosion or thermal degradation.